For example, the formation of a finer resist pattern on a substrate by a photolithography technique including an exposure step using a KrF excimer laser or an ArF excimer laser as a light source as compared with a conventional technique has been known in the production of a semiconductor element. Light of the KrF excimer laser or ArF excimer laser (incident light) incident to a resist film before the formation of the resist pattern is reflected on a surface of the substrate to generate a standing wave in the resist film. Due to the influence of the standing wave, the shape of pattern edge collapses. Therefore, a resist pattern having a desired shape cannot be formed. That is, it is known that the presence of the standing wave can cause variation in dimension of the resist pattern and resolution failure.
In order to suppress the generation of the standing wave, various techniques of providing an anti-reflective coating that absorbs incident light between the resist film and the substrate have been proposed. In particular, an organic anti-reflective coating formed from a light absorbing substance, a polymer, and the like has been variously investigated as the anti-reflective coating from the viewpoint of simple film-forming properties. For example, an anti-reflective coating of acrylic resin having a hydroxy group as a cross-linking reactive group and a light absorbing group in the molecule, and an anti-reflective coating of novolac resin having a hydroxy group as a cross-linking reactive group and a light absorbing group in the molecule have been proposed.
Properties required for the organic anti-reflective coatings include large absorbance to light and radiation; no intermixing with a photoresist layer as an upper layer (insoluble in a photoresist solvent); no diffusion of low molecular weight substance from the anti-reflective coating to the photoresist layer as the upper layer during heating and baking; and a dry etching rate higher than that of a photoresist.
In recent years, in order to solve a problem such as wiring delay in a semiconductor device with advance in refinement of pattern rule in the semiconductor device, a dual damascene process has been investigated as a process for forming a wiring on the semiconductor device. In a substrate in which the process is adopted, a via hole is usually formed. In this case, an anti-reflective coating is formed on the substrate that has a large aspect ratio. When a substrate having a recess on a surface is used in the production of a semiconductor element as described above, it is necessary that the anti-reflective coating have properties of a gap-filling material or a flattening material that can flatten a substrate having a recess by embedding.
For example, Patent Documents 1 and 2 propose an underlayer film-forming composition for lithography containing a compound having a protected carboxyl group and a compound having an epoxy group as a composition that can flatten a substrate having a recess on a surface by embedding.